Terminology
Terminology
At Birk Manufacturing, we believe that clear communication is essential. This page is designed to ensure that you understand the key terminology commonly used on our website or when speaking to our team members about your needs for flexible heaters, sensors, and thermal solutions.
If you need more information to understand any of the topics or terminology discussed here or elsewhere on our website, please reach out to us.
| Term | Definition |
|---|---|
| Accuracy | A statement that is used to define the largest allowable error in a device or system. It is an indication of how close measured values are to true values. It can be expressed in both measured units and in percentages. |
| Adhesion | The atomic or molecular attraction at the interface of two materials. |
| Adhesive | Material used to attach similar or dissimilar materials to each other. See also Pressure Sensitive Adhesive (PSA). |
| Acrylic | A thermoset adhesive that is effective for applications with less demanding temperature requirements. This material has excellent mechanical strength, radiation resistance, and low outgassing properties, which makes it suitable for long-duration space missions |
| Alpha (⍺) | Indicates the basic change in resistance in a material for each ⁰C change in temperature. It is a defining parameter for resistance temperature detectors (RTDs). Alpha (α) is essentially the slope of the RTD's resistance-temperature curve within a range. |
| Amperes (Amps) | A measure of current through the heater. |
| Balco Foil | A brand name for a thin sheet of nickel-iron alloy whose resistance changes predictably with temperature making it suitable for resistance temperature detectors (RTDs). |
| Black Kapton® | A carbon filled polyimide made by DuPont. The material has both high absorptance and high emittance. |
| Borders and Spacing | Border: distance between the edge of a heater and the nearest heating trace (typically 0.020” min.) Spacing: distance between adjacent heating traces (typically 0.010” min.) |
| Bond Ply | A thermally conductive and electrically isolating material used to bond other materials together. It facilitates the decoupling of bonded materials with mismatched thermal coefficients of expansion and can withstand multiple lamination cycles. |
| Butyl | A rubber insulator material resistant to water and most harsh chemicals. It is available in varying thicknesses. |
| Compensating Loop | A control mechanism that adjusts temperature measurements by accounting for lead wire resistance, ensuring accurate readings from RTD sensors |
| Conformal Coating | A specially engineered polymeric film-forming product that protects circuit boards, components, and other electronic devices from harmful environmental conditions like moisture, thermal shock, static, vibration, and contamination. |
| Continuity | The presence of a complete path for electric current to flow between two points. |
| Constantan Foil | A thin sheet of copper-nickel foil with high thermal conductivity. It is available in various widths and thicknesses. |
| Copper Foil | A thin sheet of copper foil with excellent electrical conductivity, malleability and corrosion resistance. It is an essential material used in the manufacturing of printed circuit boards (PCBs) and flex circuits. |
| Cover Lay | A thin film made of a polyimide film and a flexible adhesive layer that insulates and protects the exposed conductors of a flexible circuit. |
| Cupron | A thin sheet of copper-nickel foil, often used for its excellent electrical conductivity and malleability, particularly in applications such as printed circuit boards, flex circuits, and flexible heaters. |
| Desiccant | A substance which can be used for drying purposes because of its affinity to water. It is used in packaging to protect from moisture and humidity. |
| Die Cut | A manufacturing process that is used to create complex shapes and cutouts in heater substrates or insulation layers. |
| Dielectric | A nonconductor of electricity, an insulator. |
| Dielectric Strength / Hipot (Breakdown Potential) | Dielectric strength: the highest electric field an insulating material can withstand without losing its insulating characteristics. Hipot: A high potential test where a voltage is applied to a heater to verify material dielectric strength and check for damage to insulation. |
| Drain Wire | An uninsulated wire used in a cable construction as a ground connection. |
| Duplex Construction | A cable or wire constructed with two insulated conductors running in parallel or twisted together. |
| EMI shielding | The use of materials or technologies to block electromagnetic waves from interfering with a device or space. The goal is to create a barrier that prevents electromagnetic interference (EMI) from causing unwanted signals or noise. Can be done in wire/cable harness and/or heater/sensor circuitry. |
| Emittance | A material’s ability to radiate heat energy. A perfect blackbody has an emittance of 1 at all wavelengths. |
| Encapsulation | The process of completely entrapping and encasing a termination or component in a substance. Typically, encapsulation refers to an insulating material surrounding and sealing an object. |
| Epoxy | A thermosetting polymer and insulating material used to encapsulate components, sensors, and lead termination areas. It is typically mixed with a catalyst and cured in an oven or at room temperature. It is applied in liquid form, cured hardened. |
| Etched Foil Heater/Sensor | A heater/sensor constructed with an etched foil circuit pattern using photolithography and chemical etching process. |
| FEP (Fluorinated Ethylene Propylene) | A thermoflow adhesive used in extreme environments due to its high temperature and low outgassing capabilities. |
| Foil Backing | A value-added option for heaters and sensors enhancing heat distribution and uniformity. It gives heaters and sensors the ability to form and hold shape, allowing for intimate contact and superior heat transfer. |
| Ground | A conducting connection to earth or to some other large conducting object. Its purpose is to maintain an earth potential on the conductors connected to it, and to conduct the ground current to and from the earth. |
| Grounded Junction | A specific type of thermocouple junction in which the sheath and conductors are welded together. A physical process of spontaneous heat transport from hotter (i.e. having a higher temperature) bodies or parts of bodies to cooler ones. |
| Heat Transfer | A physical process of spontaneous heat transport from hotter (i.e. having a higher temperature) bodies or parts of bodies to cooler ones. |
| Heat Transfer Coefficient | A measure of how efficiently heat is conducted from the heater to its application surface. |
| Heater Zones | Regions of higher and lower resistance (or wattage), within a flexible heater, created by a custom etched foil pattern. |
| Hermetically Sealed | Any type of sealing that makes a given object (i.e. a sensor) airtight, preventing the passage or seepage of gases, liquids, or solids in or out. |
| Inconel Foil | A thin sheet of foil made from a nickel-chromium-based superalloy, known for its high strength, resistance to corrosion and oxidation, and ability to maintain strength at high temperatures. |
| Insulation Resistance | A measure of how well insulating material prevents the flow of electricity. It's an important factor in the safety and reliability of electrical systems. It is the ratio of the applied voltage to the total current flow between two conductors separated by insulation or any conductor and the sheath. |
| Kapton® | The DuPont trademark name for polyimide film. |
| Laminate (Noun) | A product made by bonding together two or more layers of material with an adhesive. |
| Laminate (Verb) | To unite layers of material with adhesive. |
| Lamination | The process of bonding two materials together - typically layers of a polyimide (Kapton®). |
| Leads over the cover | Lead pads exposed through cover lay with laser and encapsulated in epoxy, conformal coating, RTV. |
| Leads under the cover | Lead wires encapsulated under cover lay. |
| Loop Resistance | The total resistance of a circuit or path formed by two conductors looped at one end. Measured in ohms (Ω). |
| Mega | A prefix meaning million, or 1x10⁶. The symbol is ‘M’. |
| Mica | An insulator material capable of reaching 1200°F (600°C) |
| Microvolt (µV) | One millionth of a volt (1x10⁻⁶ volt). |
| Millivolt (mV) | One thousandth of a volt (10⁻³ volt). |
| Monel Foil | The trademarked name for a group of nickel-copper alloys, typically containing around 63 – 67% nickel and 28 – 31% copper, along with trace amounts of other elements like iron, manganese, carbon, and silicon. |
| Multi-layer | Multiple layers within one heater assembly. This can include multiple heater layers, sensor layers, shielding layers (electrical and radiation). |
| Negative Temperature Coefficient | A characteristic of a material in which a decrease in resistance accompanies an exposure to increased temperatures. |
| Noise | Unwanted electrical interference picked up on a signal cable. |
| Ohms (Ω) | A measure of resistance of a heater or sensor. |
| Outgassing | The process of emitting volatile substances from a material. |
| Over-molding | The process of adding an additional material layer over a component for enhanced protection or durability. |
| Parallel Pair | A wire construction where two single conductors are laid parallel. |
| PI | Polyimide, a substrate (i.e. – Kapton®, Apical®, Upilex®) |
| PID Controller | A device that maintains precise temperature control by adjusting power based on feedback from temperature sensors. |
| Polyimide | A high-performance dielectric film commonly used as insulation for thin film heaters. Available in a variety of chemistries, thicknesses - with or without adhesive layers. |
| Polyimide Flexible Heater | An etched foil heating element pressed between two layers of polyimide film with a thermal adhesive. |
| Positive Temperature Coefficient | A characteristic of a material in which an increase in resistance accompanies exposure to an increase in temperature. |
| Post Cure | A process that involves exposing a cured material to high temperatures to improve its physical properties. It's often used to finish the curing process for silicone rubber and resin. |
| Power Conditioning/ Thermal Cycling | Power conditioning: a test where a set power is applied to a heater for a time frame to ensure proper safe operation. Thermal Cycling: a test where a heater is exposed to changing temperature extremes to check durability, performance and safe operation. |
| Pre-formed | A heater/sensor formed to a preliminary shape and fit prior to installation. |
| Pressure Sensitive Adhesive (PSA) | An adhesive backing that can be bonded to a heater or sensor surface and allows the heater/sensor to be applied to many different surfaces. |
| Protection Tube | A tube that is designed to protect a sensor from any harsh environment or process conditions. It is also used to isolate legs of sensors when necessary. |
| Redundant Circuit | A circuit that provides multiple paths or components to perform a function, enhancing reliability and fault tolerance by ensuring that if one part fails, another can take over. Used primarily in aerospace and space applications. |
| Repeatability | The ability of a sensor or system to indicate the same reading under repeated identical conditions. |
| Resistance | A measure of how much material or component in an electrical circuit opposes the flow of electric current, measured in ohms (Ω). Dimensions, material, and temperature all influence resistance. |
| Resistance Temperature Detector (RTD) | A type of temperature sensor with a significant temperature coefficient where resistance changes as its temperature changes. |
| Response Time | The time required for a sensor to reach 63.2% of the step change in temperature for a particular set of test conditions. |
| Ro | The resistance measurement taken on an RTD at 0⁰C. |
| Room Temperature Vulcanizing (RTV) | A type of silicone that cures at room temperature. It is typically used to over mold, encapsulate and protect components, and termination areas. |
| Shaded Watt Density | The ability to incorporate multiple zones of varying watt density within one heater. |
| Sheild | A metallic foil or braided wire layer surrounding a conductor or a group of conductors to prevent electrostatic or electromagnetic interferences from external sources. |
| Shrink Tubing | A type of plastic tubing that shrinks when heated to create a protective seal around wires, cables, and other components. |
| Silicone Rubber | An excellent insulator that comes in a variety of forms, thicknesses, cured/uncured, colors, weave, etc. |
| Silicone Flexible Heater | An etched foil or wire wound heating element vulcanized between two layers of silicone rubber. |
| Solder | A metal or metallic alloy used when melted to join metallic surfaces. |
| Spot Weld | A type of electric resistance welding used to weld various metal products through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current. |
| Stability | The ability of a heater or sensor to maintain a consistent output with the application of a constant input. |
| Stainless Steel Foil | A thin, flexible sheet of stainless steel alloy primarily composed of iron and chromium, with other elements like nickel or molybdenum often added to enhance its properties. |
| Substrate | The base layer(s) upon which a process is to be performed (i.e. – silicone rubber, polyimide) |
| Surface Resistivity | An electrical resistance parameter for thin conducting layers. The surface resistivity is given by the bulk resistivity divided by the film thickness and is independent of the cross-sectional area of the layer measured. |
| Temperature Calibration Point | A temperature at which the output of a sensor is compared or determined by comparison against a standard. |
| Temperature Coefficient of Resistance (TCR) | A description of how much a material’s resistance changes for every degree Celsius (or Kelvin) change in temperature, typically expressed in parts per million (ppm) per ⁰C. |
| Temperature Range, Continuous | An engineer’s best judgment of recommended temperature ranges that a material can withstand, continuously, without degradation. Continuous exposure is described as periods of hours or longer. |
| Temperature Range, Intermittent | An engineer’s best judgment of recommended temperature ranges that a material can withstand, intermittently, without degradation. Intermittent exposure is described as periods of seconds or minutes. |
| Tera | A prefix meaning trillion, or 1x10¹². The symbol is ‘T’. |
| Terminals | A device (block or pin) that ends a wire or cable and connects it to another component. |
| Thermal Conductivity | The ability of a material to conduct heat. |
| Thermal Fuse | A fuse which breaks (melts) at a certain high temperature to open the circuit and shut the heater off (will not turn back on again). |
| Thermal Gradient | The distribution of differential temperatures in and across an object. |
| Thermal Shock | A sudden and rapid temperature change that causes stress in a material or component, potentially leading to cracking, delamination, or failure due to uneven expansion or contraction. |
| Thermistor | A temperature-sensitive resistor used for monitoring and controlling heater temperature. |
| Thermocouple | A temperature sensor made from two dissimilar metals, often used to measure temperatures in heating applications. |
| Thermofoil™ Heater | A thin, flexible heating element consisting of an etched foil resistive element laminated between layers of flexible insulation. |
| Thermopile | Multiple thermocouples connected in series so that alternate junctions are at the reference and measuring points. The result of this type of arrangement is an increased output for a given temperature differential. |
| Thermostat (T-stat) | A temperature control device that opens or closes the circuit based on temperature. Turns the heater on or off repeatedly. |
| Thermowell | A closed-end tube that will accept a temperature sensor and provide a pressure-tight connection at the well’s point of installation. |
| Transducer | A device that receives and transmits energy. In many instances, the energy that is received is transmitted in a different form. |
| Transmitter | An externally powered device that transmits a signal from a thermocouple or an RTD via a two-wire current loop. |
| Twisted Pairs | A type of cabling system that consists of two insulated copper wires twisted together. The twisting reduces electromagnetic interference (EMI) and crosstalk between pairs of wires. |
| Volts (V) | The energy applied to a heater (a unit of measure). The electrical potential difference between two points in a circuit, which drives the flow of electric current. |
| Vulcanization / Vulcanize | The process of factory bonding silicone rubber heaters/sensors to a variety of surfaces. |
| Watts (W) | The power generated by the heater (a unit of measure). |
| Watt Density | The watts divided by the area (in square inches) of a heater (measured in Watts per square inch)The measurement of the total electrical power distributed across the geometric area of the heater. Thus, Watts per unit area, or Watts/Area. |
| Watts per Square Inch (W/in²) | The measurement of the heat output density of a heater. |
| Watts per Square Centimeter (W/cm2) | The Watt-density when the heater area is measured in square centimeters (cm2) |
| Wire Wound Heater/ Wire Wound Sensor | The process of using resistance wire to weave a circuit pattern of a heater and/or sensor. |
